Secrets and Lies: Digital Security in a Networked World is divided into three chapters. The first one gives a good overview on threats and systems. The next chapter is the biggest of the three and focuses on security technologies which can be used against digital threats. The third and last chapter covers methodologies which can be used in order to build a more secure environment.

In his former book, Applied Cryptography, Schneier wrote about mathematical solutions which seems to be the key to absolute security, at least in theory. In Secrets and Lies he revises his point of view and put it in a more realistic way by applying it to reality. A chain is only as strong as its weakest link it says, which is absolutely true and could be seen many times in past and probably will be seen many times in future. There are reams of threats one have to encounter - systems are connected to the internet, employees could be blackmailed, buildings can be intruded, hardware gets old and vendors could conceal vulnerabilities in their products. In order to know the weakest link one have first to know what the chain consists of. In this first part Schneier explains this and more, and gives some further suggestions, such as possible scenarios and reasons why an attacker might be motivated.

The second and biggest part of this book covers many topics which are important in order to protect against various threats. They are presented in several small parts and discuss their pros and cons and are backed up by samples.